The present invention relates to a method and apparatus for detecting a motor error of a motor driven power steering (MDPS), and more particularly, to a method and apparatus for detecting a motor error of MDPS, which quickly detects disconnection of a line connected to each phase of a motor of the MDPS, thereby securing the safety of a driver.
Since MDPS generates an assist thrust through a motor, each upper logic calculates a proper command to generate steering torque.
That is, as illustrated in FIG. 1, when MDPS operating logic detects a motion of a steering wheel by a driver, a command calculated through steering performance logic is transmitted to torque limit logic to limit excessive torque, and steering torque is generated by a command calculated through motor control logic.
At this time, when a line connected to a phase of the motor is disconnected in the motor control logic, a current cannot flow through the corresponding phase. Thus, the MDPS does not normally operate, but fail-safe logic is driven.
Conventionally, in order to detect disconnection of each phase line of the motor, D-axis and Q-axis current errors of the motor have been used, steering wheel rotation speed and current variation ratio have been reflected, or a current of each phase has been sensed and checked.
In such a method, however, the disconnection was detected through the Q-axis command current of the motor. Thus, during high-speed traveling, the detection was impossible. Furthermore, since the steering wheel speed and current variation ratio are reflected to detect disconnection, the detection was impossible when the steering wheel is slowly operated, for example, when a vehicle is driven at low speed or stopped for a while. Thus, the method has limitation in detecting disconnection.
Furthermore, since the current of each phase of the motor has an 0 A value at a specific motor position, it is difficult to distinguish a normal situation from disconnection only through the Q-axis command current of the motor and the measured current of each phase of the motor.
The related art of the present invention is disclosed in Korean Patent Laid-open Publication No. 10-2012-0033171 published on Apr. 6, 2012 and entitled “Driving control method for electrical short in motor of motor driving power steering”.